<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .box{
            width: 50vw;
            height: 50vh;
            background-color: red;
        }

    </style>
</head>
<body>
    <div class="box" ></div>
    

</body>
</html>